Means for counteracting centrifugal force moments in rotary cylinder barrel engines



July 31, 1962 T. BUDZICH 3,046,906

MEANS FOR COUNTERACTING CENTRIFUGAL FORCE MOMENTS IN ROTARY CYLINDER BARREL ENGINES Filed May 31, 1957 2 Sheets-Sheet 1 a i; a 2 5 Q i 03 E N 5 3 f R R" i H Q8 ui 3 w 1 T In 1 a P [q s a? 1 I L -I Lr L INVENTOR w H Tadeusz Budzich r L L L BY ATTORNEYS July 31, 1962 T. BUDZICH 3,046,906

MEANS FOR COUNTERACTING CENTRIFUGAL FORCE MOMENTS IN ROTARY CYLINDER BARREL ENGINES 2 Sheets-Sheet 2 Filed May 51, 1957 Pic-3.3

INVENTOR TadeuszBudzich BY 7 SW ATTORNEYS 3,046,906 BEANS FOR COUNTERACTING CENTRIFUGAL FORE MGNENTS EN ROTARY CYLINDER BARREL ENGINES Tadensz Bndzich, Watertown, N.Y., assiguor to The New York Air Brake Company, a corporation of New Jersey Filed May 31, 1957, Ser. No. 662,723

' 6 Clm'ms. (Cl. 103-162) This invention relates to fluid pressure engines and more particularly to engines of the rotary cylinder barrel longitudinally reciprocating piston type. As used herein, the term engine means a device which is capable of operating as either a pump or a motor.

In engines of this type, the pistons are carried by the rotary cylinder barrel in a circumferential series of longitudinal cylinder bores which sequentially register with inlet and exhaust ports in a valve member as the barrel rotates. The pistons usually coact with an adjustable inclined cam plate which moves them on their discharge strokes in timed relation to said sequential registration and regulates the length of their strokes in accordance with its angular position. \Inherent in these devices is the fact that at any instant of time, the centers of gravity of the pistons lie in a plane extending in a direction parallel to the face of the cam plate. Since the pistons are rotating with the cylinder barrel they are subjected to centrifugal forces which, because of this inherent characteristic, produce a moment on the cylinder barrel which varies directly as the length of the piston strokes. This moment, which acts about an axis extending in a direction normal to the axis of rotation, tends to tilt the cylinder barrel relatively to the valve member, thereby causing undesirable wear and leakage between these parts. In those engines having a plate type valve member which abuts against an end face of the cylinder barrel, the effect of this tilting can be serious and therefore it is in these engines that the present invention has particular application.

The object of this invention is to provide, in engines of the type mentioned, a device for counteracting the centrifugal force moment acting on the cylinder barrel. In its preferred form, the invention comprises a balancing port located in the face of the valve plate which abuts the cylinder barrel and a flow passage connecting this port with the high pressure port of the valve plate. The area and location of the balancing port are so correlated with the pressure prevailing in said valve plate port that the force exerted on the cylinder barrel by the hydraulic fluid which issues from the balancing port produces a constant moment about the cylinder barrel support having a magnitude intermediate the limiting magnitudes of the centrifugal force moment and acting in opposition to this moment. The specific magnitude of the balancing moment depends on the intended use of the engine. For example, if the engine will operate mostly at the 50% 'displacement condition, the balancing moment would have a magnitude equal to the centrifugal force moment under this condition. This means that during operation at greater r smaller displacements a net moment in one direction or the other would be present, but the maximum value of this net moment will be but a fraction of what it would have been in the absence of the invention. Obviously, in its most refined state, the invention includes means for programming the magnitude of the balancing moment in accordance with variations in the magnitude of the centrifugal force moment. However, for most engines of this type it is thought that the preferred embodiment represents a satisfactory compromise between complexity and performance.

The preferred form of the invention will now be de- "ice scribed in relation to the accompanying drawings, in which:

FIG. 1 is an axial section of a variable displacement engine employing the invention.

FIG. 2 is an end view of the face of the valve plate which abuts the cylinder barrel and showing the location of the balancing port.

FIG. 3 is an axial section of the balancing port plunger.

FIG. 4 is an end view of the face of the plunger shown in FIG. 3.

Although the preferred embodiment of the invention can function as either a pump or a motor, it will be described as if it were serving in the former capacity.

Referring to FIG. 1, the engine comprises a housing having separable sections 11 and 12 formed with mating flanges which are secured together by bolts 13. The right end of housing section 12 is bored to receive a plate valve 14 which forms a slip fit with the bore. As shown in FIG. 2, the valve plate 14 contains arcuate inlet and discharge ports 15 and 16 which communicate respectively through passages 17 and 18 with inlet and exhaust ports formed in the housing. Iournalled in the housing section v 11 and in the valve plate 14 is a two-part drive shaft hav ing telescoping sections 19 and 21 joined by splines 22. A rotary cylinder barrel 23, formed with an axial bore 24, freely encircles the drive shaft and is connected to it by torque tube 25 and splines 26 and 27. A spring 28, surrounding the torque tube and reacting between the splines 26 and the adjustable seat 29, urges the cylinder barrel into contact with the valve plate. The cylinder barrel contains a circumferential series of longitudinal cylinder bores 30 which extend through the barrel and receive pistons 31. Each piston 31 carries a spherical head 32 at one end for universally supporting a piston shoe 33. The cylinder barrel 23 is supported laterally by a spherical enlargement 34 formed on the drive shaft and centered at the intersection of the axis of the drive shaft and the plane of the centers of spherical piston heads 32. This enlargement is in great circle engagement with the surface of axial bore 24, whereby the cylinder barrel is free to tilt and to move in the longitudinal direction relativelyto the shaft. The method of supporting and driving the cylinder barrel is more fully disclosed and claimed in applicants copending application Serial No. 656,574, filed May 2, 1957, now U.S. PatentNo. 2,925,046, issued February 16, 1960.

The piston shoes 33 are in contact with an adjustable cam plate 36 which, together with nutating plate 37, functions to reciprocate pistons 31 in a well known manner. The nutating plate 37 is formed with a central spherical recess 38 arranged to seat on the spherical outer surface 39 of the collar 41. The center of the spherical surface 39 is coincident with the center of spherical enlargement 34. The collar 41 is restrained against axial movement by annular shoulder 42 located on the shaft. The piston inertia loads transmitted from the nutating plate 37 to the shaft by shoulder 42, are in turn carried into housing section 12 by a thrust bearing 43. This method of handling the inertia loads is more fully described and claimed in applicants copending application Serial No. 665,387, filed June 13, 1957, now U.S. Patent No. 2,953,099, issued September 20, 1960.

The cam plate 36 is supported by yokes and trunnions (not shown), located at opposite sides of housing section 12, for angular adjustment about an axis which extends in a direction normal to the drive shaft axis and intersects it at the center of spherical enlargement 34. The lower end of the cam plate is universally connected with spring plunger 44 and with motor piston 45 by connecting rods 46 and 47 respectively. A conventional control valve 48 transmits pressure fluid to the motor piston 45 aoaasoe for varying the inclination of cam plate 36 in response to variations in pump discharge pressure.

Located in valve plate 14 are two diametrically opposed bores 49 and 51 which extend through the plate and open through the leakage groove 52 and two of the conventional dynamic pads 53. Tightly pressed into the bores 49 and 51 are plungers 54 and 55, respectively, whose end faces are in the plane of the face of the valve plate Hand in abutment with the end face of the cylinder barrel 23. The face of plunger 54 contains a balancing port 56 (see FIG. 3 and 4) which communicates with the discharge port 16 of the valve plate via longitudinal bore 57, radial passages 58 and passage 59. Coaxial with the balancing port is an annular groove 61 which forms, with the port and the outer periphery of the plunger, two annular lands 62 and 63. A plurality of radial slots 64 connect this groove and the leakage groove 52 of the valve plate 14. The slots, groove and lands formed in the face of plunger 54 provide a definite area over which the fluid issuing from balancing port 56 can act. In the absence of these elements, it would be difficult to predict the nature of the pressure gradient between the balancing port and the nearest loW pressure area on the face of the valve plate and consequently the balancing force could not be precisely determined. The plunger 55 is solid and has a plane uninterrupted end face. This plunger serves to make the pattern of the dynamic pads 53-symrnetrical and, as described below, provides for the easy substitution of a plunger 54 in the case of the overcenter engine.

When the engine is operating, the cylinder barrel 23 will be rotating and carrying with it the pistons 31. The pistons will be subjected to centrifugal forces which act through their centers of gravity, indicated in FIG. 1 at points 65. Since, at any instant of time, these centers of gravity lie in a plane extending in a direction parallel with the surface of cam plate 36, it is apparent that these forces will produce a moment on the cylinder barrel 23 tending to tilt it in a clockwise direction (as viewed in 7 FIG. 1) about its support 34. It will also be apparent that the magnitude of the centrifugal force moment depends on the angular position of the cam plate 36; varying from zero, when the cam plate is vertical, to a maximum when the plate is in its maximum inclined position, as shown.

The fluid issuing from balancing port 56 exerts a force on the cylinder barrel 23 equal to the pressure in discharge port 16 multiplied by the area of the balancing port. The fluid also acts on the area of annular land 62 and exerts an additional force on the barrel approximately equal to the area of the land multiplied by one-half the pressure in discharge port 16. These two forces produce a constant counterclockwise moment on the cylinder bar- 7 rel 23 which acts in the same plane and about the same axis as the resultant centrifugal force moment. The radial distance between the axis of the cylinder barrel and the balancing port is correlated with the areas of this port and annular land 62 and with the pressure prevailing in discharge'port 16 sothat the magnitude of the balancing moment is one-half the maximum value of the centrifugal force moment. In this Way, thecentrifugal force moment will be balanced at the half-displacement position of the cam plate but will be underbalanced or over balanced when the cam plate is in any other position. However, the magnitude of this unbalance will never be greater than one-half the maximum value of the centrifugal force moment.

In environments where the output of the pump is continuously varying between no-delivery and full-delivery, this balance of the centrifugal force moment at the 50% stroke position of the cam plate is satisfactory. However, in some installations, such as in aircraft where the pump operates at 25% capacity most of the time, it is desirable to balance this moment at some other position of the cam plate. This change can be efiected by varying the radial location of the balancingport or by using a plunger having different port and land areas.

In those engines which are reversible either by changing the direction of rotation of the drive shaft or by interchanging the flow connections for the valve plate ports 15 and 16, the balancing port 56 would be connected to both of the ports 15 and 16, and the engine would incorporate automatically shiftable valves for connecting the balancing port and the high pressure port and for isolating it from the low pressure port. A simple means for accomplishing this result comprises a check valve mounted in each of the two flow passages connecting the balancing port and the ports 15 and 16 of the valve plate,

In those engines which are reversible by moving the cam plate to opposite sides of a neutral zero-displacement position, two diametrically opposed balancing ports 56 must be used because the direction of the centrifugal force moment reverses as the cam plate moves through neutral.

'In the engine illustrated, this means that the solid plunger would be replaced with a plunger 54 having a half ancing port 56 connected with the valve plate port 15. When the cam plate is positioned to the left of the vertical, as shown'in FIG. 1, valve plate port 16 would be the high pressure port and the centrifugal force moment would be opposed by the moment generatedv by the balancing port 56 located above the shaft axis. On the other hand, when the cam plate is moved to the right of the vertical, port 15 would become the high pressure port and the centrifugal force moment, which now would 7 act in a counterclockwise direction, would be opposed by the clockwise moment generated by the balancing port located below the shaft axis.

The preferred form of the invention is thought to pro-- vide satisfactory balancing for most engines of the type described. However, in some engines, it may be necessary to balance the centrifugal force moment at all positions of the cam plate. In this case, the engine could include a throttle valve for automatically varying the pressure transmitted to the balancing port in accordance with variations in the centrifugal force moment.

As stated previously, the drawings and description relate only to a preferred embodiment of the invention. Since many structural changes can be made in this embodiment without departing from the inventive idea, the following claims should provide the sole measure of the scope of the invention.

What is claimed is:

1. In combination with an engine of the type including a rotary cylinder barrel containing a plurality of longi tudinal cylinder bores and a piston reciprocable in each bore, a valve plate in abutment with an end face of the cylinder barrel for sequentially transmitting fluid to and from the cylinder bores, and a cam, plate adjustable between minimum and maximum angles of inclination with respect to a plane that is normal to the axis of rotation of the cylinder barrel for moving the pistons on their discharge strokes and for varying the length of these strokes, and in which the centers of gravity of the pistons lie in a common plane inclined with respect tosaid normal plane so that the centrifugal forces generated by the pistons produce a tilting moment on the cylinder barrel, the angle of inclination of said common plane and consequently the magnitude of said tilting moment varying with the angle of inclination of the cam plate, the improvement which comprises a balancing port located in the face of the valve plate and opening against the end face of the cylinder barrel; an annular groove surrounding said balancing port and forming therewith an annular pressure land; means for supplying pressure fluid to the balancing port; and means for venting the annular groove, the balancing port being so located that the forces applied to. the cylinder barrel by the fluid issuing from it and flowing across the pressure land produce a counteracting moment on the cylinder barrel that acts in a direction opposite to and about the same axis as said tilting moment, and the areas of balancing port and pressure land being so correlated with the pressure supplied thereto that the magnitude of the counteracting moment is intermediate the minimum and maximum values of said tilting moment.

2. In combination with an engine of the type including a rotary cylinder barrel containing a plurality of longitudinal cylinder bores and a piston reciprocable in each bore, and a valve plate in abutment with an end face of the cylinder barrel for sequentially transmitting fluid to and from the cylinder bores, and a cam plate adjustable between minimum and maximum angles of inclination with respect to a plane that is normal to the axis of rotation of the cylinder barrel for moving the pistons on their discharge strokes and for varying the length of these strokes, and in which the centers of gravity of the pistons lie in a common plane inclined with respect to said normal plane so that the centrifugal forces generated by the pistons produce a tilting moment on the cylinder barrel, the angle of inclination of said common plane and consequently the magnitude of said tilting moment varying with the angle of inclination of the cam plate, the improvement which comprises a balancing port located in the face of the valve plate and opening against the end face of the cylinder barrel; and means for transmitting pressure fluid to the balancing port, the balancing port being so located that the force applied to the cylinder barrel by the fluid issuing from it produces a counteracting moment on the cylinder barrel that acts in a direction opposite to and about the same axis as said tilting moment, and the area of the balancing port being so correlated with the pressure supplied thereto that the magnitude of the counteracting moment is intermediate the minimum and maximum values of said tilting moment.

3. In combination with an engine of the type including a rotary cylinder barrel containing a plurality of longitudinal cylinder bores and a piston reciprocable in each bore, and a valve plate in abutment with an end face of the cylinder barrel for sequentially transmitting fluid to and from the cylinder bores, and in which the pistons are moved on their discharge strokes by a cam plate inclined with respect to the axis of rotation of the cylinder barrel, whereby the centers of gravity of the pistons lie in a common plane inclined with respect to a plane normal to said axis so that the centrifugal forces generated by the pistons produce a tilting moment on the cylinder barrel, the improvement which comprises a balancing port located in the face of the valve plate and opening against the end face of the cylinder barrel; an annular groove surrounding said balancing port and forming therewith an annular pressure land; means for supplying pressure fluid to the balancing port; and means for venting the annular groove, said balancing port and land being so located that the forces applied to the barrel by the fluid issuing from the port and flowing across the land produce a moment on the cylinder barrel which acts in a direction opposite to and about the same axis as the tilting moment produced by the centrifugal forces generated by the pistons.

4. In combination with an engine of the type including a rotary cylinder barrel containing a plurality of longitudinal cylinder bores and a piston reciprocable in each bore, and a valve plate in abutment with an end face of the cylinder barrel for sequentially transmitting fluid to and from the cylinder bores, and in which the pistons are moved on their discharge strokes by a cam plate inclined with respect to the axis of rotation of the cylinder barrel, whereby the centers of gravity of the pistons lie in a common plane inclined with respect to a plane normal to said axis so that the centrifugal forces generated by the pistons produce a tilting moment on the cylinder barrel, the improvement which comprises a balancing port located in the face of the valve plate and opening against the end face of the cylinder barrel; and means for transmitting pressure fluid to the balancing port, the balancing port being so located that the force applied to the barrel by the fluid issuing from the port produces a moment on the cylinder barrel which acts in a direction opposite to and about the same axis as the tilting moment produced by the centrifugal forces generated by the pistons.

5. In combination with an engine of the type including a rotary cylinder barrel containing a plurality of longitudinally reciprocating pistons, and a cam plate adjustable between minimum and maximum angles of inclination with respect to a plane that is normal to the axis of rotation of the cylinder barrel for moving the pistons on their discharge strokes and for varying the length of these strokes, and in which the centers of gravity of the pistons lie in a common plane inclined with respect to said normal plane so that the centrifugal forces generated by the pistons produce a tilting moment on the cylinder barrel, the angle of inclination of said common plane and consequently the magnitude of said tilting moment varying with the angle of inclination of the cam plate, the improvement which comprises means for exerting a constant moment on the barrel which acts in a direction opposite to and about the same axis as the tilting moment produced by the centrifugal forces generated by the pistons and has a magnitude intermediate the minimum and maximum values of the centrifugal force moment.

6. In combination with an engine of the type including a rotary cylinder barrel and a plurality of longitudinally reciprocating pistons mounted therein and in which the pistons are moved on their discharge strokes by a cam plate inclined with respect to the axis of rotation of the cylinder barrel, whereby the centers of gravity of the pistons lie in a common plane inclined with respect to a plane normal to said axis so that the centrifugal forces generated by the pistons produce a tilting moment on the barrel, the improvement which comprises means for exerting a moment on the cylinder barrel which acts in a direction opposite to and about the same axis as the tilting moment produced by the centrifugal forces generated by the pistons.

References Cited in the file of this patent UNITED STATES PATENTS 2,161,143 Doe, et al. June 6, 1939 2,168,658 Thomas Aug. 8, 1939 2,298,850 Vickers Oct. 13, 1942 2,397,314 Grosser Mar. 26, 1946 2,733,666 Poulos Feb. 20, 1953 2,735,407 Born Feb. 21, 1956 2,847,984 Gallant Aug. 19, 1958 2,849,894 Brusdal Sept. 2, 1958 FOREIGN PATENTS 211,326 Great Britain Feb. 21, I924 

